Yepp @theworkshope, I did the reverse engineering of the Pro v3.0b after all. More or less the entire board, but some pieces are still missing, and findings needs to be tested first, so I make it in text rather than in schematics for now. Inputs are highly appreciated…
Usedful link for pinout: https://shapeokoenthusiasts.gitbook.io/shapeoko-cnc-a-to-z/anatomy-of-a-shapeoko#controller-board
V3.0b is in my opinion generally a very good design, but I wouldn’t be surprised to see a revision C with some minor adjustments.
All input signal like limit switches, FEED_HOLD and PROBE signal has got an input noise suppression filter that will also work as protection circuitry for the Atmega328 (motion controller). That´s great!
The 6 pin BitRunner connector seems to have 24V, GND and PWM used for controlling the router in ON=5V / OFF = 0V, as default or PWN (see the above link). The “PWM” signal is connected directly to 328 uP pin 15 - PB3 which is a multipurpose config options: PCINT3/OC2A/MOSI. This signal is also available on one of the ISCP connector pins (used for firmware loading).
For the remaining three signals, one seems to be unconnected, two reserved signals are connected directly from pin 22 (PC7 (INT4/ICP1/CLK0) and pin 23 (PC6 (OC.1A/PCINT8) on the ATmega16U2 (USB interface controller). For what I would guess, this is how it should be if future or now (don’t know) could be implemented as a fail safe mechanism to kill router if the motion controller gets stuck. The motion controller should only adjust router speed (as from what I’ve read is what the PWM is intended to do). The PWM frequency seems to fixed.
The reason for a possible revision C is that all three signals seems to be missing som boosters and/or protection circuitry in between the connector and the uP. I guess they are all intended to be outputs. In short: BE VERY CAREFUL NOT TO SHORTCIRCUIT ANY OF THESE WITH THE 24V! THE BUILT IN ESD PROTECTION CIRCUITRY IN THE ATMEGA328 WILL FEED THE HIGH VOLTAGE DIRECTLY TO THE 5V POWER RAIL AND POTENTIALLY KILL BOTH CONTROLLERS AND MORE.
What needs to be tested is if there is also some kind of a watchdog included like as if the signals are somehow altering during run to indicate that the USB controller and PC interface is alive and kicking.
EDIT AFTER TEST: Didn’t find any such.
X12 connector have the same signals, but with a slightly different pinout for NC, pin 22 and pin 23. The 24V, GND and PWM is mirrored from BitRunner.
The SPIO soldering pads includes PWM and the D13 is also found on the ICSP.